Insulating board and process of making the same



, the Weather.

' for ordinary purposes it is seriously -detri-' Patented Mar 2@, H923;

taeeaa TBS PATENT CODFFHQE;

GEORGE ELLIS, ST. PAUL, MINNESQTA.

msuna'rin'e scam) Ann rnocnss or MAKING 'rjnn same.

We Drawing.

To all whom it may concern:

Be it known that'l GEORGE H. ELLIS, a citizen of the United fdtates, residin at St. Paul, in the county of Ramsey and tate of Minnesota, have invented new and useful Improvements in Processes of Making the Same, of which the following is a specification M' invention relates to improvements in insu ating boards and particularly such boards as are molded or felted from vegetable fibres. v

The object of my invention is to produce economically an efficient insulating board or block of fibrous material.

A further object is to provide such a board or block with a sizing and binder which is permanent and repellent to moisture.

A further object is to provide a foundation for stucco or plaster which will retain its rigidity and efiiciency when exposed to After extensive experiments I have discovered that it is possible to apply directly to the fibres of which such aboard is composed, a bitumen such as asphalt or coal tar, during the process of pulping the material for such board, and that by so doing a stronger and lighter product and one better adapted to form a foundation for stucco or plaster may be secured.

It has been common practice in paper making, as well as in the manufacture of insulating board, to use what is known as engine sizing such as rosin soap precipitated with aluminum sulphate, and to a less extent casein precipitated with a reagent, such as alum has been employed, but such sizings cause deterioration of the product, particularly when it is exposed to moisture, and while this susceptibility may be of small importance where the product is paper used mental to an insulating board which forms the foundation for plaster or is long exposed to the weather. Thus, an insulating material in which aluminum sulphate and rosin soap have been used will in time deteriorate because of the detrimental efiect of these agents upon cellulose. The chemilnsulating Boards and Application filed'llliarch 15,1921. Serial No. 452,523.

cal changes which takd place, gradually weaken and make, v brittle the product.

In manufacturing my insulating board l. prefer to employ an ordinary paper makers eating engine. Water, preferably hot,.together with cellular material such as waste paper, straw or wood fibres are placed in the beater in the usual proportions to form a pulp. I then add a bitumen such as coal tar or asphalt in a fluid or semi-fluid state. Twelve to fifteen per cent of bitumen (by bulk) is sufficient. It is well known that tar, asphalt and other bitumens do not mix readily with water, and ll, therefore, depend upon the mechanical action of the beater cylinder," blades and concave to paint the fibres with the bitumen while the stock is being reduced to a pulp. After the fibres have been thoroughly coated with the bitumen, the stock is removed from the heater and drained, when it'may be either felted or molded in the usual way and then dried. T have found that this process not only water proofs the fibres themselves but reduces the capillary attraction which tends to carry moisture into the insulating board. I thus eliminate frommy board all free precipitates which predispose the product to deterioration and substitute a material which is cheaper and better suited to the purpose than the rosin size, alumor casein heretofore employed. In addition to being substantially water proof and having no tendency to soften when subjectedto moisture my board has a greater number of caged air cells than boards made by rocesses heretofore known to me and it is, t erefore, lighter and better adapted for insulat- 2. lhe method of producing insulating board which consist in first placing fibrous taneously' pulped, then molding or felting the stock into a board and finally drying the same.

I 3. A board composed of vegetable fibres felted or molded with a binder of liquid bitumen, and constituting a porous, self sustaining body adapted to form abase for plaster.

In testimony whereof, I have hereunto I signed my name to this specification.

GEORGEH. ELLIS. 

